Dental impression tray



June 24, 1941'. v CQBLE 2,247,013

\ DENTAL IMPRESSION TRAY Filed June 11, 1940 I 3mm Gr eSC0b,Le/

Patented June 24, 1941 I UNITED A STATES Lucian Graves Coble, Greensboro, N. 0.

Application June I1, 1940, Serial 110.339.970

' a claims; (o1. 32-17) g 'This invention relates to improvements in dental impression trays and, particularly,to a mandibular impressiontray for taking an impression of the lower jaw of a patient who has no lower teeth remaining. V

In preparing impressions for making dental plates, it is common practice, as is well understood, to press a mass of plastic molding material against and around the gum surfaces and, especially, the ridges of the gum. For thus manipulating this mass of plastic molding material, it is placed in what is commonly referred to as a dental tray so that said material can easily be forced against the surfaces of which an impression is desired. After the impression has been made and the plastic material set, it is necessary to trim and shape the side surfaces of the impression. In most instances, the trays are of metal and, particularly in the case of a mandibular impression tray, it is quite difficult to trim or carve the surfaces of theimpression for the purpose of properly shaping the same without interference from the metal constituting the tray in which the impression is retained for purposes of proper support. Due to these difliculties, theprincipal object of the present invention is to provide a dental impression tray, and particularly a mandibular impression tray, with which an impression can be made with the greatest facility and with which that impression, when set, can be properly supported without interfering with the trimming. and shaping operations.

More specifically, the invention contemplates a mandibular impression tray of sectional construction in that it comprises a substantially U- shaped outer member of sufficient width to span the ridges of the patients gum so as to permit the plastic molding material held in the tray to be pressed against the sides and beyond the ridges, and an inner member loosely supported in the bottom of the outer member so as to become embedded in the plastic material during the making of the impression, this inner member being free to be removed with or as a part of the impression so as to properly support the impression after the latter has been taken out of the outer mem ber of the tray. This inner member of the tray is comparatively narrow so that, when the impression is removed from the outer member and supported only by the inner member, the impression projects an appreciable distance beyond the side edges of the inner member so that the side surfaces of the impression can be trimmed and properly shaped without the implement used for that purpose contacting or engaging against the comparatively narrow supporting inner member.

With these andother objects in view, themvention consists in certain details of construction and combinations and arrangements of parts; all as will hereinafter be more fully described, and the novel features thereof particularly pointed out in the appended claims. 1 j

In the accompanying drawing illustrating the preferredembodiment of the present invention, 1 Figure 1 is a top'plan viewof the fully assem bled tray; i

- Fig. 2 is a similar view with the inner member removed; I

Fig. 3 is a perspective view of the inner member of the tray; and Fig. 4 is a sectional view Fig. 1.

In the tray as illustrated in the present instance, there is an outer'member l0 and an inner member ll, these members being substantially U-shaped so as to, correspond in contour to that of the gum of the'lower jaw. As'iswell under on the line 4-4 of stood, the tray is dished to accommodate a quantity of moldable plastic material sufficient to have at least a portion of the lower jaw imbedd'ed therein in order that an impression of thewhol'e' lower jaw, and particularly the ridges thereof, can be taken. To facilitate handling of the tray, as when forcing it, together with the molding material, against and around the gum, the outer member In is provided with a handle I2 which may be rigidly attached to said outer member.

In the present invention, the outer member ID has one or more recesses or openings l3 adapted to loosely receive a corresponding number of positioning pins M on the under face of the inner member II. This is the only means of attachment between the inner and outer members as it is intended that the inner member shall become embedded in, and practically become a part of, the molded material constituting the impression, and be removed from the outer member l0 along with the impression. In other words, the inner member II is loosely held in the outer tray 10, the positioning pins l4 merely preventing lateral or endwise shifting of the two members. To insure the inner member I I becoming embedded in and adhering to the impression formed by the plastic material, said member may be formed with means for interlocking with the molded material. For instance, a plurality of openings I 5 may be formed therein. By reason of the plastic material protruding into these openings [5, the inner member will be securely interlocked with an impression made with the tray.

It will be observed that the inner member is comparatively narrow so that, while an ample quantity of plastic material for the desired impression can be placed in the assembled tray,

support the impression after the latter has been removed from the tray proper and, at the same time, the reduced width of said inner member permits the side surfaces to be trimmed and shaped without danger of the instrument used in that operation coming into contact with the metal of which the inner member is made. Not

only may the inner member be of considerably lesswidth than the finished impression, but it may also be made somewhat shorter without detracting from thesupport it gives the impression for the purpose of preventing breakage and distortion of the impression during the remainder of the processor handling thereof for properly and accuratelyfinishing it. The use of this readily removableinner member II, as indicated above, permits the use of an outer member of such dimensions as to carry suificient molding material necessary to insure obtaining impressions the desired distance, so to speak, upwardly around the sides of the gum surfaces.

Due to the reduced dimensions of this inner member I I, it is deemed preferable to form the same of metal, although other materials which will impart suificient rigidity to the membermay be utilized. The present tray is especially adapted for use in making impressions of patients gums from which all teeth have been extracted, but it'rwill be understood that, in many instances, it will serve with the same degree of efficiency where there are one or more remaining teeth.

What I claim is:"

-lQA'dental tray comprising a substantially U shaped outer 'member having a depression therein of suflicient breadth to span the ridges of the gum of the lower jaw of a patient whereby a mass of plastic molding material in said depression can be forced against and at least partially beyond the sides of said ridges for making an impression thereof, and an inner substantially rigid U-shaped member loosely received in the bottom of said depression adapted to be embedded in the bottom surface of the plastic material and to be removed from said outer member together with the impression formed by the molded material whereby the latter will be supported by the inner member, said inner member being of less width than the molded material to leave the side surfaces of the impression fully exposed and to facilitate trimming and shaping of the side surfaces of the impression.

2. A dental tray comprising an outer member of suflicient width and depth to span the ridges of the lower gum of a patient and permit a mass of plastic molding material to be forced against thesides of the ridges and beyond the ridges to form an impression thereof, said member having a recess therein, a handle attached to said tray, an inner member loosely supported in said outer member, and a projection on said inner member engaging in said recess, said inner member being removable from the outer member together with said impression to support the latter and, said inner member being of less width than the impression to facilitate trimming and shaping the side surfacesof said impression.

3. A 'mandibular dental tray comprising an outer section having a base and opposite side walls spaced to span the ridges of a patients gum for forcing a molding material against and beyond the ridges, and an inner section detachably held on the base of the outer section between the side walls, said'inner'section being of less width than the base andradapted to extend substantially the length of the bottom of a body of molding material used in the tray, and said inner section being removable with the molded material from the outer section to support the mold with the side surfaces of the latter exposed throughout their length whereby they can be trimmed and shaped without contacting said inner section.

; LUCIAN GRAVES COBLE. 

